1. Field of the Invention
This invention relates to a novel melange-colored sheet having at least on one surface a layer of super-entangled ultrafine fibers and/or ultrafine fiber bundles comprising at least two types of ultrafine fiber, both of which are branched from the ultrafine fiber bundles and/or multi-core fibers of the inner portion. The bundles and/or multi-core fibers are different in color so that the surface presents a melange-color. This invention also relates to a method of producing said novel melange-colored sheet.
2. Related Application
This invention is related to and is an improvement upon the invention disclosed in co-pending U.S. application Ser. No. 479,970 filed Mar. 29, 1983, now U.S. Pat. No. 4,476,186.
3. Description of the Prior Art
A typical example of conventional grained artificial leather is obtained by forming layers of elastic polymer such as polyurethane on fiber substrate and providing a pattern to the surface of the polymer layer by embossing or forming layers of grain patterned elastic polymer on the fiber substrate by transfer coating. Japanese patent application publication No. 27636/81 describes an artificial leather which comprises a very thin polyurethane surface and an ultrafine fiber substrate, but fails to teach any melange-colored and super-entangled ultrafine fiber surface. Laid-open Japanese patent application publications Nos. 33221/78 and 106668/79 describe melange-colored artificial suede comprising ultrafine fiber naps extending from differently colored ultrafine fiber bundles. However, these references are silent about super-entangled surfaces of differently colored ultrafine fibers. Laid-open Japanese patent application No. 66188/82 describes a melange type sheet composed of two types of fibers, but the surface is buffed before dyeing to obtain artificial suede. Moreover it fails to teach ultrafine fiber bundles constituting the inner portion of the sheet.
In diversifying such technique of making grained artificial leather, attempts have been made to obtain melange-colored artificial leathers corresponding to the natural leather dyed with an aniline type dyestuff which shows varying shades, lighter and darker in various parts.
The aniline (synthetic dye) finish shows effective varying shades of surface color in the natural leather. However, the melange-colored grained sheet of the present invention includes not only such effect but also presents a complex grain pattern in two or more kinds of color such as in melange dyeing, which is hard to obtain in natural leather.
Processes have been used for providing different colors in conventional artificial leathers, as mentioned above, such as forming a layer of a mixture of elastic polymers containing different pigments, or coating unevenly with a gravure roll or spraying paints of different colors, However, these have both the disadvantages of falling-off of the provided different color layer due to abrasion or deterioration of the resin or vehicle, and the surface has a rubber-like or plastic feel due to the presence of the elastic polymer, coupled with a plastic appearance, all being much inferior to dignified aniline-finished natural leather.
Furthermore, even aniline-finished natural leather has the disadvantages of easily becoming bruised and easily stained because it is colored by splashing, which causes short life without constant maintenance. It is also unable to provide further complexity in color or a high-grade feeling with a sober color.
The present invention overcomes the disadvantages of conventional artificial leathers, such as falling-off of the melange-colored layer and the rubber-like or plastic feeling, as well as obtaining a complicated melange-colored effect, not obtainable even from natural leather. It further has the advantage of easy care.